Del. Fam. Ct. R. Civ. P. 13
(a) Compulsory counterclaims. A pleading shall state as a counterclaim any claim which at the time of serving the pleading the pleader has against any opposing party, if it arises out of the transaction or occurrence that is the subject matter of the opposing party's claim and does not require for its adjudication the presence of third parties of whom the Court cannot acquire jurisdiction, except that such a claim need not be so stated if at the time the action was commenced the claim was the subject of another pending action.
(b) Permissive counterclaims. A pleading may state as a counterclaim any claim against an opposing party not arising out of the transaction or occurrence that is the subject matter of the opposing party's claim.
(c) Counterclaim exceeding opposing claim. A counterclaim may or may not diminish or defeat the recovery sought by the opposing party. It may claim relief exceeding in amount or different in kind from that sought in the pleading of the opposing party.
(d) Counterclaim maturing or acquired after pleading. A claim which either matured or was acquired by the pleader after service of that party's pleading may, with the permission of the Court, be presented as a counterclaim by supplemental pleading.
(e) Omitted counterclaim. When a pleader fails to set up a counterclaim through oversight, inadvertence, or excusable neglect, or when justice requires, the pleader may by leave of Court set up the counterclaim by amendment.
(f) Cross-claim against coparty. A pleading may state as a cross-claim any claim by one party against a coparty arising out of the transaction or occurrence that is the subject matter either of the original action or of a counterclaim therein, or relating to any property that is the subject matter of the original action. Such cross-claim may include a claim that the party against whom it is asserted is or may be liable to the cross-claimant for all or part of a claim asserted in the action against the cross-claimant.
(g) Joinder of additional parties. Persons other than those made parties to the original action may be made parties to a counterclaim or cross-claim in accordance with the provisions of Rules 19 and 20.
(h) Separate trials; separate judgments. If the Court orders separate trials as provided in Rule 42(b), judgment on a counterclaim or cross-claim may be rendered when the Court has jurisdiction to do so, even if the claims of the opposing party have been dismissed or otherwise disposed of.
Del. Fam. Ct. R. Civ. P. 13